1. Field of the Invention
The present invention relates to an oil pan for internal combustion engine.
2. Description of the Related Art
As an oil pan provided on the bottom portion of an internal combustion engine, an oil pan including a baffle plate having a guide face inclined downward from its central portion toward its peripheral portion and a plurality of oil discharge holes formed in the outer peripheral portion of this guide face intermittently at positions in contact with the inner peripheral face of the oil pan, this baffle plate being located above an oil sump formed by deep-drawing the bottom portion of the oil pan main body for collecting oil, has been proposed conventionally.
In the oil pan having the baffle plate as disclosed in conventional patent document 1, returned oil which after lubricating sliding faces of an internal combustion engine, that is, sliding faces of a cylinder and piston and bearing portions of a crank shaft and the like, floats in space of a crank case and drops down is received by a baffle plate and returned to an oil sump through the guide face, oil discharge holes and then the internal peripheral face of an oil pan main body in this order. Thus, an impact generated when the returned oil drops to oil in the oil sump is small thereby preventing bubbles from being generated in oil of the oil sump.
Patent document 1: Japanese Utility Model Application Laid-Open No.HEI3-52312
Generally, the baffle plate attached to the bottom end of the cylinder block or above the oil pan has a function of a structural component which suppresses vibration and the like generated in the opening direction of the cylinder block. However, because in the aforementioned conventional oil pan, the baffle plate is attached above the oil pan main body as a separate member and it is formed only partially above the oil pan, it cannot be said that it exerts the function for suppressing vibration sufficiently.
The present invention has been accomplished to improve the vibration suppressing effect of the internal combustion engine. According to a first aspect of the present invention, there is provided an oil pan for internal combustion engine comprising an upper portion to be attached to the bottom portion of a cylinder block directly or through an adaptor plate and a lower portion provided on the bottom of the upper portion, in which a baffle plate is formed integrally downward of the upper portion and an oil supplying means for supplying sucked oil to respective portions of the internal combustion engine is provided, wherein the upper portion is constituted of side walls connecting the cylinder block with the lower portion and the baffle plate, the baffle plate is comprised of the sucking portion which is the oil supplying means provided substantially in the center and an inclined portion which is inclined downward toward the side wall with the sucking portion as its vertex and communicating opening portions are formed near the side walls of the inclined portion to communicate the cylinder block with the lower portion.
According to a second aspect of the present invention, preferably, a plurality of tightening holes for fastening the oil pan to a cylinder block with tightening means are provided in the top portion of the side wall of the upper portion, the tightening holes are located between respective cylinders along the arrangement direction of the cylinders formed in the cylinder block, longitudinal ribs are formed vertically at positions corresponding to the positions of the tightening holes on the inner side of the side wall while the longitudinal ribs are inclined from the top end of the side wall to said baffle plate.
According to a third aspect of the present invention, preferably, the communicating opening portions are provided between the longitudinal ribs in the arrangement direction of the cylinders and on both ends in a direction perpendicular to the arrangement direction of the cylinders.
According to a fourth aspect of the present invention, preferably, an oil passage for introducing oil sucked by a sucking portion of the baffle plate into the oil supplying means is formed integrally in the bottom of the upper portion.
The oil pan for the internal combustion engine of the present invention comprises the upper portion and the lower portion provided on the bottom of the upper portion and the baffle plate is formed integrally on the bottom of the upper portion and an oil supplying means is provided. The upper portion is comprised of side walls connecting a cylinder block with the lower portion and the baffle plate. The baffle plate is comprised of a sucking portion in the oil supplying means provided substantially in the center and the inclined portion which is inclined downward toward the side walls with the sucking portion as its vertex. The communicating opening portions for communicating the cylinder block with the lower portion are formed near the side walls of the inclined portion. Thus, because the baffle plate is formed integrally with the bottom of the upper portion, as compared with a case where the baffle plate is provided with a separate member, higher stiffness can be secured so that vibration and radiating sound can be suppressed more easily, thereby the quantity of components being reduced and the weight of the internal combustion engine being reduced.
The top portion of the side wall of the upper portion includes a plurality of tightening holes for fastening the oil pan to the cylinder block with tightening means. The tightening holes are provided so as to be located between respective cylinders in the arrangement direction of the cylinders formed in a cylinder block and the longitudinal ribs are formed vertically on the inner side of the side walls at positions corresponding to the positions of the tightening holes. The longitudinal ribs are formed in such a shape in which it is inclined from the top end of the side wall to the baffle plate. Consequently, the longitudinal ribs connect the side walls with the baffle plate thereby intensifying the stiffness of the baffle plate.
Because the communicating opening portions are provided between the respective longitudinal ribs in the arrangement direction of the cylinders and on both ends in the direction at right angle to the arrangement direction of the cylinders, oil dropping onto the baffle plate can be introduced from the right/left sides and front/rear sides of the outer periphery of the baffle plate to the lower portion located downward quickly under a guide of the longitudinal ribs, and consequently, heat of hot oil is discharged to the atmosphere through the side face and bottom face of the lower portion so that oil is cooled excellently.
Because the oil passage for introducing oil sucked through the sucking portion of the baffle plate to the oil supplying means is formed integrally on the bottom of the upper portion, oil can be supplied excellently to the oil supplying means through the oil passage and further, because the oil passage is formed integrally, the stiffness of the baffle plate is improved thereby the vibration suppressing effect of the internal combustion engine being improved.